Piston pin and method of forming same



R. R. TEETOR PISTON PIN AND METHOD OF FORMING SAME Dec. 31, 1929.

Filed Sept. '7, 1926 I a mo/ wmhja. Yegtoz 0/ j y 5 tab/Z6615.

Patented Dec. 31, .1929

UNITED STATES 11.11.1211 a. rnnron, or mennsrown, INDIANA.

rrsron rm AND METHOD or ro'mrme sum Application filed September 7, Serial No. 1238,78 8.

My invention relates to piston pins and the method of forming the same.

In internal combustion engine construction, such as that used in connection with automobiles, it is a well known practice to.

operatively connectthe pistons to their respective connecting rods by means of piston pins. The usual piston pin consists of a single-walled tubular iece which has a wall 10 thickness generally cl about one-fourth to one-sixth the diameter of the pin. In most instances such pins are made 0 a high grade carbon steel which is capable ofreceiving heat treatment and case hardening, it being 5 necessarily required that the pins be very hard on the outer surface and be ground to a fine finish to provide a bearing surface with smooth, even and long wearing qualities. Such piston pins should also be light in no weight without sacrificing any of'the foregoing desirable features.

The usual method of manufacturing these pins is to make them from either steel tubing or from solid bar which is drilled out in the center to form a tube. Of these two existing methods, the latter is used in the majority of instances, particularly, in the manufacture of high grade piston pins. Much difliculty is experienced in the manufacture of piston pins fromsteel tubing due to the fact that it is exceedingly diflicult to obtain steel tubing which has a uniform chemical structure.

More particularly, steel tubing is formed very often with seams which, when heated, as open up and render the tubing useless for piston pins. Both of these methods require very exactin operations and are very expensive, all 0 which necessarily cause a high cost of maintenance and repair.

It is the object of my invention to eliminate the foregoing objectionable features involved in the-manufacture of piston pins and to provide a highly eflicient piston pin which is very simple in constructlon, exceedingly ea which will stand up under 0 crating conditions for a maximum length 0 time, whereby,

maintenance and repair costs are reduced to a minimum. 7

so Another object is to provide a piston pin porting the connecting rod 5. Any of the and inexpensive to manufacture, and

comprised of'two kinds of metals joined together by a single casting operation'to form the complete pin.

A further object is to provide an inexpens1ve manner of forming piston pins wherein a hardened jacket is cast around and to a piece of steel tubing to form a complete double-walled piston pin.

Other and further objects and advantages will become apparent as this description proresses and by reference to the appended rawlng showing my novel piston pin and one form of apparatus for forming the same and wherein,- I

Fig. 1 is a perspective view of my novel piston pin.

Fig. 2 is a partial sectional view of a piston and connectmg' rod operatively joined together by my novel piston pin.

Fig. 3 is a vertical sectional view 'of a mold for forming the piston pin, the steel tubing being shown in position in the mold ready for casting.

Fig. 4 is a view similar to Fig. 3, the casting operation being complete.

Referring particularly to the drawing,,my piston pin (Fig. 1) may comprise integrally joined double-walled construction having the inner tubular portion 1 with the outer jacket 2 cast around and to it. The tube lis formed, preferably, of steel while the jacket 2 is formed, preferably, of cast iron; however, it is to be understood thatother suitable materials may be employed in the respective instances without departing from the scope of my invention. A manner of use of my piston pin is shown in Figure 2 which shows an ordlnary form piston 3 with the ordinary bosses 4 for carrying the pin A, such .pin sup-- several well known ways of mounting and locking the piston pin in place to operatively connect the associated parts may be employed without departing from my invention.

In Figs. 3 and 4 one form of apparatus for performing my methodof' formm a iston pin is diagrammatically illustrate eferring particularly to such figures, in forming the pm A, I may em loy a mold B, such mol being adapted to t e casting of cast iron. 10'.

The mold B may comprise the outer wall 6 adapted to receive the molding sand 7. A mold cavity may be formed in the sand 7 in the usual manner em loyed in forming casting molds and in sue a we that a cooling member may be embedded t erein. It is to be understood that any suitable cooling medium may be circulated through the member 8 viathe ipes 8 and 8 during the casting operation. 1e purpose of the cooling member 8 is to effect a rapid and predetermined coolin of the molding sand 7 in contact with t e molten metal, to quickly chill and harden to the desired extent such molten metal fed into the mold cavity, as will be discusssed more fully hereinafter.

The mold B has a cavity of substantially the diameter of the pin to be formed. In forming such pin, a piece of steel tubing, such as that illustrated by the numeral 1 (Fig. 3), of the length to be given the completed pin, is inserted concentrically in the mold cavity, the tubing being held in such predetermined concentric position by any well-known and desirable means, such as, for exam le, the concentrically rojecting portion 0 the molding sand 9 in t e bottom of the mold cavity. The piece of steel tubing 1 is formed thin, preferably, not thicker than one-half the thic ness of the completed 1n. p With the tubing 1 in osition in the mold as stated, a concentric mo d space 10 is formed around such tubing, the tubing serving in effect as a center core, for example, as the usual sand core used in casting center core castings. The mold cavity 10 may be vented in any well-known and desired manner to prevent trapping of air therein during castmg. After the tubing 1 has been placed in the mold as stated, a suitable cover, which is diagrammatically illustrated at 11, is placed above the mold, such cover having a suitable pouring mouth illustrated by the numeral 12 in communication with the mold cavit 10. It is to be understood that any wel known construction may be employed for feeding the molten metal into the mold cavity, the construction shown in the drawing being only dia rammatic for the purpose of illustration. ith the parts in position as llustrated in Figs. 3, the mold is ready for the pouring operation. As the molten metal is poured into the pouring mouth 12, it passes thence through a suitable passa e or passages, such as thedpassa s 13 an 14, to the cavity 10 surroun ing t e tubing 1 and fills the same (Fig. 4) As the cavity 10 is filled, the molten metal is quickly cooled due to the cooling action of the sand 7 cooled by the member 8, and the metal is thereby quickly. chilled and hardened, sufficient and rapid cooling of the sand and metalbeing provided to accomplish this. The cooler steel tube 1 also aids in this cooling and chilling action.

- a whole.

Furthermore, as this action takes place the outer cast iron jacket 2 is to the tube. 1, firmly set to the same as th. metal sets in contact therewith, as is "well understood in the art, so that these two walls, 1 and 2, or the completed pins are, in effect, integrally joined. Upon the completion of the foregoing, the completed pin is removed fronr the mold and given the desired iine finish shown in Figs. 1 and 2 in any wellknown manner. The cast iron jacket 2, so formed and finished, provides the desired hard and finally finished outer bearing surface, while the inner tube ortion 1 adds supporting strength and rigidity to the pin as With the cast iron jacket formed in the manner described and shown, the entire wall is onl of such thickness that the pin as a whole is ight in weight.

From the foregoing, it is obvious that I have provided a highly efiicient piston pin in an inexpensive manner, such pin being light of weight and possessed of long wearing qualities, all of which tends to reduce maintenance and repair costs to a minimum.

Having thus described my invention, what I claim is:

1. A thin-walled, light weight piston pin. of the character descrlbed, which comprises an inner, thin, steel tubular shell section of a thickness substantially one-half the total thickness of the pin wall, and a chill-hardened cast iron shell section around said steel shell section intimately joined therewith by castin to form in effect a single wall structure, t e outer surface of said cast iron shell part being finished for bearing surfaces.

2. A thin-walled light weight piston pin which comprises an inner, steel tubular shell part of a uniform thickness throughout substantially one-half the total thickness of the pin wall, and a chill-hardened cast iron shell art of uniform thickness throughout the ength of the pin cast around said steel shell part and intimately joined therewith to form a single wall structure which is formed only of said two shell parts, and the outer part of said cast iron shell part being finished for bearing urposes.

3. A t in-walled, light weight piston pin of the character described, which comprises an inner, thin, steel tubular shell section, and

a chill-hardened cast iron shell section around said steel shell section intimately joined therewith by casting to form in effect a single wall structure, the outer surface of said castifron shell part being finished for bearing suraces.

In testimony whereof, I have subscribed my name.

RALPH R. TEETOR. 

